1. Field of the Invention
This invention relates to polyester compositions. More particularly, this invention relates to polyester patching compositions which have incorporated therein pigments which indicate when the catalyst and polyester have been uniformly mixed and further indicate when the composition has cured sufficiently to permit further working of the patched area.
2. State of the Art
It is well known in the art that pigments added to the polyester composition, whether added to the hardener (catalyst) or resin compound, provide a method of determining the uniformity of the blend of resin and hardener. Although this has been very useful to the trade, it has not solved the problem of determining when the cure takes place and when it is completed. There is a need for a method that will tell the user when the cure has been completed and "finish work" can be done on the cured part. The instant invention will provide the casual, unskilled user in the field with a visual method which will indicate when he has a cure and thus he may proceed with the finishing work or removal of the part from a mold.
Most of the use of polyester compositions has been in the Automotive body filler area. However, increased application are being made in such fields as boat making and repair, sheet molding compounds, open or closed molds, hand laying or chopper gun and other polyester or epoxy application.
Pigments added to the hardener have been known to the trade which uses polyester resins. The pigmented hardener is added to the polyester to give a visual indication of the uniformity of the mix. If the color is blended uniformly, then the hardener and resin are blended uniformly. This uniform blending is necessary to obtain a uniform cure. Pigments added for this purpose are disclosed in U.S. Pat. Nos. 3,181,991 and 3,182,026. These patents do not teach a procedure for determining the cure, only that the blend is uniform. Pigment added to the hardener (catalyst) or resin for determining the cure of polyesters and epoxy by the disappearance of color or fading are disclosed in U.S. Pat. Nos. 4,164,492 and 3,390,121. These do not offer a color change to indicate the cure time but rather a color disapperance or fading and are difficult to discern.